Over the course of the past week, I have had several hundred energy stolen from me by this game, and it is probably the single most rage-inducing aspect of the energy system, and the thing most likely to make me quit.
The way the game gobbles up energy with no concern whatsoever for circumstance is unacceptable:
Selecting "join party" and being thrown into a party on a Vendor level or seconds away from clearing a normal level. -10 Energy for negligible or no gain whatsoever.
Disconnects, game bugs, and other quirks that result in wasted energy. Not a minute ago I accepted a party invitation from a guild mate, clicked yes, only to have my screen fade black and nothing happen. The game sure remembered to eat my 10 energy though!
If this were an arcade and I had just put a quarter into a machine, only to have the game randomly demand that I enter another quarter because of unfortunate timing, or for the machine to spontaneously reboot itself on a whim, the owners of the arcade would have an angry mob of people ready to storm their office. The situation in Spiral Knights is hardly any more acceptable.
The game needs some more intelligent methods of deciding where and when to put players into an in-progress party to avoid wasted energy, and ideally some code that can figure out when the servers have died or the game bugged out and unfairly jettisoned people from a level. Yes, that presents a difficult challenge to make a system like that which cannot be exploited for free energy. That's the can of worms Three Rings brought on themselves when they decided to make a game where you can't even fart without coughing up cash currency.
It would be a great idea to set ''Join'' option that way, that you join the next avivable level, in other words, game waits for the team to clear the current level and you join the game when they advance to the next one.